A device and method for treating tissue at a treatment site. The device and method include supplying controlled energy to a heating portion of the device positioned within a tissue wall at the treatment site. The size of the heating portion and energy supplied provides for ablation of the tissue to form a cavity within the tissue wall without ablating the surfaces of the tissue wall. Treatment fluid can then be supplied through the device to the cavity to supplement growth of blood vessels or retard such growth of the treatment site. The device can also be used to create an injury zone at a treatment site without ablating tissue, wherein the injury zone can be injected with treatment fluid. The device and method has use anywhere within the body, especially in the regions of the heart.